Lighting plays a vital role in photography, particularly in studio photography. For settings such as portraiture, it is common to use a number of studio lights to illuminate the subject and the backdrop. For a particular setting, the lighting may include a main light, providing the main lighting on the subject, one or more side or fill lights, filling in along the sides of the subject, and a back light illuminating the backdrop.
Commonly used studio lights comprise an incandescent lamp which provides steady illumination at a first, low intensity, and a flashtube, typically filled with Xenon gas or a combination of gases, which provides flash illumination at a second, much higher intensity but for a very brief period. The incandescent lamp in the studio light allows the photographer to position and adjust the lighting, while the flashtube provides high intensity illumination for recording the image. The flashtube in the studio light may be triggered from an electrical signal such as from a wire connection to a camera or other studio light, a wireless connection using radio frequency (RF) transmitters and receivers, or may be triggered in “slave” fashion by a photosensor on the studio light detecting another flash.
Such a system of studio lights allows the photographer to set the subject, position the studio lights, and then record images.
Proper color balance, or color temperature of lighting sources is very important in color photography. Flash sources commonly have equivalent color temperatures similar to daylight, on the order of 5200-5500 degrees Kelvin (K). Commonly used incandescent (tungsten) sources have color temperatures on the order of 3200K.
In the studio setting, the photographer must perform setup using incandescent illumination, while recording images using flash illumination; the color balances of the two are quite distinct. In some settings, such as those outside the studio, the photographer may have to deal with situations with strong ambient light from tungsten or fluorescent sources, or from sunlight or other strong illumination filtered through or reflected off colored objects. In these situations, the photographer may use filters to try and correct the illumination to provide a balanced image.
Based on the fixed spectra of presently available flashes and the limitations of filters used to modify spectral content of available light, there is a need for a studio light with adjustable color temperature.